When digital imaging is considered for law enforcement, the issue of the admissibility of digital photographic evidence in court is often raised. The fact that digital photographs are more easily altered than film-based photographs is usually cited. Some believe that digital photographs are not admissible in court.
As digital imaging becomes more widely used in forensic science, knowledge of what flies — and what doesn’t — is essential.
Going Digital
Digital cameras are steadily gaining popularity within the field of forensic science, however, there are still drawbacks to the use of digital imaging within forensic science casework. One area of concern is the quality and authenticity of images.
“Digital photographs can be altered with Adobe Photoshop or any of the enhancement software programs,” says Georgia Pasqualone, MSN, MSFS, RN, CEN, DABFN, adjunct faculty member at Fitchburg State College. “When you go into court and you raise your right hand to swear that the photograph or the end product is as it was when you took the picture; that might get a little tricky.”
While technology has rapidly advanced, there are still drawbacks to digital photography as it relates to forensic science. One major drawback is the amount of time required to take multiple exposures. The delay can be in the range of two to 15 seconds, the time necessary for the light sensor to read the scene and adjust the f/stop or change the shutter speed, check the auto focus, if so equipped, and trigger the flash. It also takes several seconds for a digital camera to perform other processes once the image has been taken. There is usually a four- to nine-second delay when the camera is converting the image into digital form, compressing and saving the image.
“It doesn’t come into play unless you’re actually at a scene or taking action photographs, but digital cameras do not have a shutter speed fast enough to photograph action,” says Pasqualone. “The camera has to think for a couple of seconds as opposed to a single lens reflex (SLR) camera, where you can get multiple sequential shots. I can do that with my Nikon, but I cannot do that with my digital camera. Sometimes you can get as many as three shots in a row, but you can’t get more than that. The camera has to start thinking again.”
Another drawback to the concept of digital photography is image resolution. Digital cameras are fairly inexpensive; however, if an impressive image is the objective, it probably won’t be found for less than $300. When comparing a traditional camera to a digital camera in the price range of $300, in most cases the traditional camera will be far superior in quality and performance.
Conversely, digital imaging does have its advantages over traditional film-based photography. “Digital makes things very sleek, very convenient, very compact,” says Pasqualone. Providing instant gratification, you can take the photo and then view it. “If you didn’t get the shot, you know you didn’t get it, as opposed to film, where you think you’ve got it and may have bracketed for the correct exposure, but you don’t truly know until you get the photos back from the processing lab. If you’ve screwed up, it’s too late.”
Another decided advantage to digital cameras is the elimination of carrying, changing and processing rolls of film. “You can take hundreds of photos on one memory card if it has a large enough capacity,” says Pasqualone. “There’s an advantage to not having to carry around and change rolls of film. The other advantage is you don’t have to take the film, maintain a chain of custody, bring it to a processing lab, have them developed and then get the prints back to the police department or case file.”
The Federal Level
Federal Rules of Evidence, Article X (Contents of Writings, Recordings, and Photographs), Rule 101 defines writings and recordings to include magnetic, mechanical or electronic recordings. Rule 101 states that if data are stored in a computer or similar device, any printout or other output readable by sight, shown to reflect data accurately, is an “original.” A “duplicate” is defined as a counterpart produced by the same impression as the original...by mechanical or electronic re-recording ... or by other equivalent techniques which accurately reproduces the original. Rule 103 (Admissibility of Duplicates) states a duplicate is admissible to the same extent as an original unless a genuine question is raised as to the authenticity of the original or in the circumstances it would be unfair to admit the duplicate in lieu of the original. This means a photograph can be stored digitally in a computer, that a digital photograph stored in a computer is considered an original, and that any exact copy of the digital photograph is admissible as evidence.1
Rules of evidence for specifics on the admissibility of digital photographs vary by state.
Relevance and Authentication
The principal requirements to admit a photograph, either digital or film-based, into evidence are relevance and authentication, according to the Recommendations and Guidelines for the Use of Digital Image Processing in the Criminal Justice System produced by the FBI.2
Unless the photograph is admitted by the stipulation of both parties, the party attempting to admit the photograph into evidence must be prepared to offer testimony that the photograph is an accurate representation of the scene. This generally means that someone must testify that the photograph accurately portrays the scene as viewed by that witness.
The main areas of concern which must be addressed when considering digital imaging as it pertains to forensic science are: image enhancement, image restoration and image compression.
Image Enhancement
Any process intended to improve the visual appearance of an image falls under the category of image enhancement. This includes processes that have a direct counterpart in the traditional silverbased photographic lab, and those that can be accomplished only through the use of a computer.
Traditional enhancement techniques are those techniques that have direct counterparts in traditional darkrooms. They include contrast and brightness adjustment, color balancing, cropping and dodging and burning. These traditional and accepted techniques are employed to achieve an accurate recording of an event or object.
Source: http://www.forensicfocusmag.com/articles/3b1feat2.html
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